I have a question, I have a Weber Silver C. I want to make sure that the grates are clean. I went through the original cast irons from H.D. they ended up more rusty that useful, I just picked up the porcleine iron grates. I clean the with steel wool every other week, I heat them before and after each use. Do the flavorizor bars need the same attention? In the past I have noticed them getting rusty quickly also.Weber says they don't need the attention, however I am not sure I want the same turkey flavor on my salmon steaks or NY strip steak

NEVER! use steel wool or steel brushes on porcelin coated grates. If the residue on the grates hasn't turned mostly to ash when you clean it you're not letting it burn long enough after you've finished cooking. Sometimes a sauce with a high concetration of sugar burns on pretty good but then you probably over sauced the food on the grill.

Let it burn with all burners on high for at least 10 min. after you finish. (Make sure you set a timer, there's such a thing as too clean also. You learn the hard way when you suck up a just filled tank.)

I let it cool down pretty good 'cause the coating is softer if it's very hot, then use one of those synthetic grill scrubbies (3M) to get most of the chunks. Wipe down the grates and just about anything else you can reach with a very hot, very wet crummy towel.

As for the flavorizer bars they are goning to change color due to the extreme high heat. They'll never look new again. I replaced mine with stainless and every now and then i just throw 'em in the dishwasher on the pots and pans cycle.

I'm going to go another direction from Yardburned here. I leave all the crap and residues on the grates until the next time I'm grilling. The extra coating provides extra protection for your grates from the elements etc. BEFORE you grill next time light her up, get the heat high (I go for 600+), overkill I know but hey... Everything will turn to ash. Then just brush it off. Stick with Brass brush, you can't go wrong with brass. Just make sure you let the temp go back down before you cook. After that I take care of my cleaning when I oil the grate ala Steve with a paper towel and oil. Works like a charm.
I clean the excess ash off the flavorizers as I notice buildup about every month (I use my grill alot!) Don't worry about passing on the flavor from the flavorizer bars, once everything is turned to ash the flavors are gone anyway. I've never put them in the dishwasher as my wife would probably shoot me, although it is a good idea (after scraping of course), I have a pressurewasher at my disposal so thats what I use. I lay my stainless grates and flavorizer bars on the driveway and let the psi do the work for me. I don't know if I'd trust this with coated grates/bars though. Would the coating come off? Dunno.
Changes in color are normal, just think about it like seasoning a cast iron pan.

I am the same as Grand Scale. I turn the grill off when I am done and do not worry about it until I grill next and then get it up to 500+ for about 5-10 minutes and then use a brass brush on the grates. I have a Broilmaster grill and it does not have flavorizer bars but a flavor screen that I use a pressure washer on about every two months and I grill 3-4 nights per week.

Yeah, yeah yeah! I didn't say I washed 'em every time . Just when they get really funky. If you use it often enough (2-3 meals a day ha, ha) you just don't need to clean 'em if you pre-heat it properly. I have a Sears (Grand Hall) six burner 66,000 BTU which I have tweaked using Weber flavorizer's 'cause the one's from Sears got too many holes in 'em and let too much stuff drip through instead of "vaporizing" it. It just seemed to fill up the drip pan too quickly. Most of the time the juices just burn off but if you cook a lot of stuff at medium or low heat the bars can develop a crust. Fortunately with enough use at higher heat levels this crud wll burn off without any further thought.

I agree with the medium heat buildups on the flavorizers. Espescially if, as Yardburner, states earlier if you use a lot of sugar based sauces/marinades. I find that even at high heat the ash build up remains as it doesn't get wire brushed off. Thats where the powerwasher comes in. Once the build up impairs the vaporization they get a bath.

Flavorizers are a great invention, every grill should have them, wether they come with it or are added later.

IMO, the biggest mistake people make when cleaning their grill is ro try to get it too clean. Remember that you should always preheat the grill to 500 - 600 degrees before coking. That's far hotter than any nasties can survive. Now all you have to do is get rids of any particles, mostly ash, the last cook. Gently scrub with a brass brush and wipe with oil before cooking. Done! About 2 -3 times per season, clean the grease collection parts to avoid a fire.

I have had my Weber for three seasons of heavy use, and have never cleaned the flavorizers. They get hotter than the grate! When they rust enough to start allowing juices to flame, I'll replace them, probably with SS.